1. Field of the Invention
The present invention relates to pipe connectors, particularly, but not exclusively, for use in connecting pipe sections of a pipe string for use in drilling. More particularly the invention relates to an improvement in the pipe connectors described in British Pat. No. 1573945 and in U.K. Patent Application Publication Nos. 2033518A and 2113335A.
2. The Prior Art
In British Pat. No. 1573945 there is described a pipe connector comprising a tubular pin member having a frusto-conical outer peripheral surface and a tubular box member having a frusto-conical inner peripheral surface corresponding to the frusto-conical outer peripheral surface of the pin member and which overlies that surface when the members are engaged together. In use, the two members are telescoped together and are axially locked together by interengageable annular projections and grooves provided on the noted peripheral surfaces, the projections and grooves being spaced apart along and extending the full length of the two surfaces.
In telescoping the two members together, the members are initially telescoped until surface contact is made between at least portions at the ends of the overlapped portions of the members to provide seals. Then fluid under pressure is preferably supplied between the members to expand the box member and/or contact the pin member, while at the same time an axial force is applied to the members to bring them together and interengage the projections and grooves. To disengage the members, fluid under pressure is again supplied between the members to expand the box member and/or contract the pin member to progressively bring the projections out of the grooves and so permit the members to be moved axially apart. However, for the pressurized fluid to be effective, seals must be maintained at both ends of the overlapped frusto-conical surfaces. Additionally, it has been found that if there is any tendency in either of the two members to deviate from a circular cross section during this expansion/contraction, the resulting ovality of the members will effectively break the seal so that the pressure of the fluid is dissipated and the members cannot then be disengaged.